Medium transport unit, recording apparatus, and image reading apparatus

ABSTRACT

A medium transport unit includes an upstream route in which a print sheet is transported, a first switchback route, a second switchback route, a first guide route, a second guide route, a guide flap configured to switch the route so that the print sheet in the upstream route is transported either toward the first guide route or toward the second guide route, a first discharge route from which the print sheet in the first switchback route is discharged, a second discharge route from which the print sheet in the second switchback route is discharged, and a downstream route passing between the first switchback route and the second switchback route and having an upstream end connected to a junction of downstream ends of the first discharge route and the second discharge route.

BACKGROUND

1. Technical Field

The present invention relates to a medium transport unit configured totransport a medium such as a print sheet, a recording apparatus providedwith the medium transport unit, and an image reading apparatus providedwith the medium transport unit.

2. Related Art

Examples of an image forming apparatus (recording apparatus) providedwith a paper reversing apparatus (medium transport unit) configured toreverse and transport a print sheet (medium) in the related art includea configuration, for example, disclosed in JP-A-9-12198. The paperreversing apparatus provided in the image forming apparatus as describedabove is configured to reverse the print sheet with a switchbackmechanism.

In other words, the paper reversing apparatus includes a first reversingpaper guide and a second reversing paper guide arranged with apartitioning plate interposed therebetween, and a third papertransporting channel and a fourth paper transporting channel extendingrespectively from the first reversing paper guide and the secondreversing paper guide respectively, joining together at downstream endsthereof, and connected to an upstream end of a downstream sidetransporting channel.

When print sheets are fed to the first reversing paper guide and thesecond reversing paper guide alternately from an upstream sidetransporting channel, the print sheets fed to the first reversing paperguide are reversed in the course of being transported in the third papertransporting channel and are fed to the downstream side transportingchannel. In contrast, the print sheets fed to the second reversing paperguide are reversed in the course of being transported in the fourthpaper transporting channel and are fed to the downstream sidetransporting channel.

The paper reversing apparatus as described above is configured in such amanner that the third paper transporting channel and the fourth papertransporting channel pass outside the first reversing paper guide andthe second reversing paper guide, respectively. Therefore, four routesincluding the first reversing paper guide, the second reversing paperguide, the third paper transporting channel, and the fourth papertransporting channel are arranged side by side. Therefore, there arisesa problem of an increase in size of the apparatus.

SUMMARY

An advantage of some aspect of the invention is to provide a mediumtransport unit, a recording apparatus, and an image reading apparatuswhich can be reduced in size.

The invention provides a medium transport unit including: an upstreamroute in which a medium is transported; a first switchback routearranged on the downstream side of the upstream route; a secondswitchback route arranged on the downstream side of the upstream route;a first guide route configured to guide the medium in the upstream routeto the first switchback route; a second guide route configured to guidethe medium in the upstream route to the second switchback route; a guideswitch unit configured to selectively switch the route so that themedium transported through the upstream route is transported to one ofthe first guide route and the second guide route; a first dischargeroute configured to discharge the medium from the first switchbackroute; a second discharge route configured to discharge the medium fromthe second switchback route; and a downstream route passing between thefirst switchback route and the second switchback route and having anupstream end connected to a junction of downstream ends of the firstdischarge route and the second discharge route.

In this configuration, the routes arranged side by side are composed ofthree routes including the first switchback route, the second switchbackroute, and the downstream route, so that a reduction in size of theapparatus is enabled.

In the medium transport unit, preferably, at least one of a conditionthat a length of the first discharge route is shorter than a length ofthe first switchback route and a condition that a length of the seconddischarge route is shorter than the second switchback route issatisfied.

In this configuration, since at least one of the length of the firstdischarge route and the length of the second discharge route can bereduced, the reduction in size of the apparatus is enabled.

In the medium transport unit, preferably, at least one of a conditionthat a length of the first guide route is shorter than a length of thefirst switchback route and a condition that a length of the second guideroute is shorter than the second switchback route is satisfied.

In this configuration, since the length of at least one of the firstguide route and the second guide route can be reduced, the reduction insize of the apparatus is enabled.

Preferably, the medium transport unit further includes a skip routediverged from a midpoint of the upstream route and join to a midpoint ofthe downstream route to guide the medium in the upstream route to thedownstream route without passing through the first guide route and thesecond guide route; and a skip switching unit configured to selectivelyswitch the route of the medium in the upstream route so as to betransported toward one of a downstream end and the skip route of theupstream route.

In this configuration, by switching the skip switching unit to the skiproute side, the medium in the upstream route can be rapidly transportedto the downstream route without passing through the first guide routeand the second guide route.

Preferably, in the medium transport unit, further includes anintermediate route connecting the downstream end of the upstream routeand the upstream end of the downstream route, and the guide switch unitselectively switches the route so that the medium transported throughthe upstream route is transported to one of the first guide route, thesecond guide route, and the intermediate route.

In this configuration, by switching the guide switch unit to theintermediate route side, the medium in the upstream route can be rapidlytransported to the upstream end of the downstream route through theintermediate route without passing through the first guide route and thesecond guide route.

Another advantage of some aspect of the invention is to provide arecording apparatus of the invention includes a recording unitconfigured to perform recording on a medium, and a postprocessing unitconfigured to perform postprocessing on the medium on which recording isperformed by the recording unit, wherein the recording unit and thepostprocessing unit are coupled by the medium transport unit.

In this configuration, a medium on which the recording is performed bythe recording unit is transported by the medium transporting unit, andis subjected to postprocessing by the postprocessing unit.

In the recording apparatus described above, the first switchback routeand the second switchback route are each configured to be capable ofreceiving a medium having a maximum recordable size for the recordingunit.

In this configuration, the medium having the maximum recordable size forthe recording unit can be received by the first switchback route and thesecond switchback route.

Further advantage of some aspects of the invention is to provide theinvention provides an image reading apparatus including: a readerconfigured to read an image on a medium; and the medium transportingunit described above, wherein the first switchback route and the secondswitchback route are each configured to be capable of receiving themedium having a maximum readable size for the reader.

In this configuration, the medium having the maximum readable size forthe reader can be received by the first switchback route and the secondswitchback route.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a perspective view of a recording apparatus of an embodiment.

FIG. 2 is a view illustrating a structural frame format of the recordingapparatus.

FIG. 3 is a view illustrating a structural frame format of a mediumtransport unit.

FIGS. 4A to 4C are schematic drawings illustrating states oftransporting a print sheet with the medium transport unit.

FIGS. 5A and 5B are schematic drawings illustrating states oftransporting a print sheet with the medium transport unit.

FIG. 6 is a view illustrating a structural frame format of an imagereading apparatus.

FIGS. 7A to 7C are structural frame formats illustrating a firstswitchback route and a second switchback route.

FIG. 8 is a view illustrating a structural frame format of the mediumtransport unit.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An embodiment of a recording apparatus will be described below withreference to the drawings.

As illustrated in FIG. 1, a recording apparatus 11 includes a printerunit 12 as a recording unit, a scanner unit 13 arranged on the printerunit 12, an automatic paper-feeding apparatus 14 arranged on the scannerunit 13, a medium transport unit 15 arranged on a side portion of theprinter unit 12, and a finisher 16 as a postprocessing unit arranged inthe medium transport unit 15 on a side portion opposite to the sidewhere the printer unit 12 is provided. An operating unit 17 configuredto perform various operations on the recording apparatus 11 is providedon the printer unit 12 at a position adjacent to the scanner unit 13.

As illustrated in FIG. 2, the printer unit 12 includes a mediumtransporting channel 20 in which a print sheet P as an example of themedium is transported, and a transport unit 21 including a plurality ofrollers (roller pairs) and configured to transport the print sheet Palong the medium transporting channel 20. The printer unit 12 includes asupporting base 22 configured to support a print sheet P from a lowerside in a vertical direction Z and a recording unit 23 configured toprint (record) an image on the print sheet P supported by the supportingbase 22 accommodated therein.

The printer unit 12 transports the print sheet P along the top of thesupporting base 22 and the medium transporting channel 20 in anorientation that a width direction X of the print sheet P corresponds tothe direction orthogonal to a paper plane of FIG. 2 and a directionintersecting the width direction X corresponds to a transportingdirection. The recording unit 23 is provided with a line head as aliquid ejection head capable of ejecting ink over the substantiallyentire area in the width direction X which intersects the transportingdirection of the print sheet P simultaneously at a lower portionthereof, and is configured to print an image by ejecting ink from anupper side in the vertical direction Z toward the print sheet Ptransported on the supporting base 22 and causing the ink to adherethereto.

The printed print sheet P is transported from the recording unit 23 tothe medium transport channel 20 by a paper discharge roller pair 24 andother plurality of transport roller pairs 25 and is discharged from amedium discharge port 26 provided at a downstream end of the mediumtransport channel 20. The print sheets P discharged from the mediumdischarge port 26 drop and are mounted on a mounting base 27 arranged onan upper side of the recording unit 23 in the vertical direction Z in astacked manner as indicated by two-dot chain lines in FIG. 2. In otherwords, the mounting base 27 sequentially receives and supports printedprint sheets P discharged and dropping from the medium discharge port26.

As illustrated in FIG. 1 and FIG. 2, the mounting base 27 has asubstantially rectangular plate shape, and is inclined so as to increasein height as it proceeds to a discharging direction Y of the printsheets P. An upper surface of the mounting base 27 corresponds to aninclined mounting surface 28, and print sheets P are mounted on themounting surface 28. A protruding portion 29 extending in thedischarging direction Y is formed on the mounting surface 28substantially at a center in the width direction X of the print sheet P.

The print sheets P mounted on the mounting surface 28 slip downward inan opposite direction to the discharging direction Y along aninclination of the mounting surface 28 and are positioned by coming intocontact at an end thereof opposite to the discharging direction Y sidewith a vertical side wall 30 provided on a lower side of the mediumdischarge port 26 of the printer unit 12 as indicated by the two-dotchain lines in FIG. 2. The discharging direction Y of the print sheet Pis inclined at an angle larger than that of the mounting surface 28 withrespect to a horizontal plane.

As illustrated in FIG. 2, the medium transport channel 20 in thisembodiment includes a medium discharge channel 34 configured totransport the print sheet P from the recording unit 23 to the mediumdischarge port 26 and a medium supply channel configured to supply theprint sheet P to the recording unit 23, and the medium supply channelincludes a first medium supply channel 31, a second medium supplychannel 32, and a third medium supply channel 33.

The medium discharge channel 34 includes a curved channel 34A and astraight channel 34B. The medium discharge channel is curved to causethe print sheet P to curve with a recording surface of the print sheet Pprinted by the recording unit 23 facing inward during the transport ofthe print sheet P printed by the recording unit 23 to the mediumdischarge port 26. The straight channel 34B transports the print sheet Pfrom the curved channel 34A toward the medium discharge port 26 in onedirection.

The medium discharge channel 34 functions as a curving and reversingroute configured to reverse the print sheet P from a state in which therecording surface thereof faces upward to a state in which the recordingsurface faces downward in the vertical direction by transporting theprint sheet P in the curved channel 34A and the straight channel 34B.Therefore, the print sheet P passes through the medium discharge channel34, which functions as the curving and reversing route, whereby therecording surface thereof faces the mounting surface 28 of the mountingbase 27, and the print sheet P is discharged from the medium dischargeport 26 onto the mounting base 27 located above the recording unit 23.

The transporting direction of the print sheet P, which is a direction inwhich the print sheet P is transported in the straight channel 34B inthe medium discharge channel 34 provided in the medium transport channel20 is one direction that the straight channel 34B has. In thisembodiment, the one direction is determined as an upward inclineddirection which rises toward the medium discharge port 26. Therefore,the inclined direction of the straight channel 34B (one direction)corresponds to the discharging direction Y of the print sheet Pdischarged from the medium discharge port 26.

In the first medium supply channel 31, the print sheet P inserted froman insertion port 36 exposed when a cover 35 provided on one sidesurface of the printer unit 12 is opened is transported to the recordingunit 23. In other words, the print sheet P inserted into the insertionport 36 is pressed against a first drive roller 38 a by a hopper 37, istransported by a rotation of the first drive roller 38 a, then ispinched between the first drive roller 38 a and a first driven roller 38b, and then is transported toward the recording unit 23 by the rotationof the first drive roller 38 a.

The second medium supply channel 32 includes a sheet cassette 39provided in a bottom portion, which corresponds to a lower side of theprinter unit 12 in an insertable/withdrawable manner. The print sheets Pmounted in the sheet cassette 39 in a stackable manner are transportedto the recording unit 23. In other words, an uppermost print sheet Pfrom the print sheets P mounted in the sheet cassette 39 in a stackedmanner is fed by a pickup roller 40, is separated into a piece by aseparation roller pair 41, then is pinched between a second drive roller42 a and a second driven roller 42 b, and then is transported toward therecording unit 23 by a rotation of the second drive roller 42 a.

In the third medium supply channel 33, in the case where both sideprinting, which is a printing option that prints images on both sheetsurfaces (paper surfaces) of the print sheet P, is performed, the printsheet P whereof printing by the recording unit 23 on one sheet surfaceis terminated is transported again to the recording unit 23. In otherwords, a divergent transport channel 44 is provided on the downstreamside of the recording unit 23 in the transporting direction of the printsheet P. The divergent transport channel 44 is diverged from the mediumdischarge channel 34 upon an operation of a divergent mechanism 43provided at the middle of the medium discharge channel 34 is provided.The divergent transport channel 44 is provided with a divergenttransport channel roller pair 45 configured to be capable of rotatingboth in a forward direction and a reverse direction on the downstreamside of the divergent mechanism 43.

The print sheet P printed on one of the sheet surfaces on one side istransported from the recording unit 23 toward the mounting base 27 onceto the divergent transport channel 44 by the divergent transport channelroller pair 45 rotating in the forward direction for the both sideprinting. At this time, a part Pe of the print sheet P transported tothe divergent transport channel 44 on a leading end side in thetransporting direction thereof projects from the medium discharge port26. Therefore, the position of projection of the print sheet P is set soas not to come into contact with the print sheets P mounted on themounting base 27 in a stacked manner when projected.

Subsequently, the print sheet P transported to the divergent transportchannel 44 is transported reversely in the divergent transport channel44 from the mounting base 27 side toward the recording unit 23 by thedivergent transport channel roller pair 45 rotating in the reversedirection. At this time, the print sheet P transported in the reversedirection is transported to the third medium supply channel 33 and istransported toward the recording unit 23 by the plurality of transportroller pairs 25. The print sheet P is transported to the third mediumsupply channel 33 and hence is reversed so that the sheet surface whichis not printed yet faces the recording unit 23. Then, the reversed printsheet P is pinched between the third drive roller 46 a and the thirddriven roller 46 b, and is transported toward the recording unit 23 by arotation of the third drive roller 46 a.

The print sheet P transported in the respective medium supply channelstoward the recording unit 23 is transported to a lining-up roller pair47 disposed on the upstream side of the recording unit 23 in thetransporting direction, and then comes into abutment at a leading edgethereof with the lining-up roller pair 47 which has stopped rotating. Aninclination of the print sheet P with respect to the transportingdirection is corrected (skew correction) by the state in which the printsheet P is in abutment with the lining-up roller pair 47 as describedabove. The print sheet P corrected in inclination is lined up and istransported toward the recording unit 23 by a subsequent rotation of thelining-up roller pair 47.

The print sheet P transported toward the recording unit 23 by thelining-up roller pair 47 is transported in a state of facing therecording unit 23 by a paper feed roller pair 48 disposed on theupstream side of the recording unit 23 in the transporting direction ofthe print sheet P, and the paper discharge roller pair 24 and thetransport roller pairs 25 disposed on the downstream side thereof in thetransporting direction. Ink is ejected onto the transported print sheetP and from the recording unit 23 facing thereto to perform printing.

As illustrated in FIG. 2, a liquid storage unit 50 configured to storeink to be supplied to the recording unit 23 provided in the printer unit12. In other words, the liquid storage unit 50 supplies ink storedtherein to the recording unit 23 via an ink supply channel, which is notillustrated, formed of a tube or the like. The recording unit 23 ejectsthe supplied ink to print an image or the like on the print sheet P. Inthis embodiment, the liquid storage unit 50 is arranged on an upper sideof the print sheet P mounted on the mounting base 27 in the verticaldirection Z. The liquid storage unit 50 is arranged so as to cover atleast part of the medium discharge channel 34 when viewing from above inthe vertical direction Z.

In other words, the upper side of the medium discharge channel 34, whichis a curving and reversing route, has an inclined shape directed in onedirection formed by the straight channel 34B continuing from the curvedchannel 34A. Therefore, a space 12S is formed in the printer unit 12 onan upper side of a portion from above the curved channel 34A to themedium discharge port 26 of the straight channel 34B having the inclinedshape.

In this embodiment, the space 12S is formed in the printer unit 12 so asto cover the medium discharge channel 34 in the width direction X whenviewing from above. The liquid storage unit 50 is arranged in the space12S so as to cover at least part of the medium discharge channel 34 whenviewing from above. In this embodiment, the liquid storage unit 50 isarranged so as to cover the entire part of the medium discharge channel34 in the width direction X when viewing from above.

A transport roller pair 25 a located on the downstream-most side of themedium discharge channel 34 in the transporting direction of the printsheet P among the plurality of transport roller pairs 25 which functionas discharge rollers provided in the medium discharge channel 34, isprovided in the space 12S at a position overlapping with the liquidstorage unit 50 when viewing from a horizontal direction.

In addition, in the space 12S, blast units 57 are provided in a spaceother than the space occupied by the liquid storage unit 50 at positionson the downstream side of the medium discharge port 26 in thedischarging direction Y of the print sheet P. The blast units 57 areconfigured to blast air in a direction of pressing the print sheet Pdischarged from the medium discharge port 26 against the mountingsurface 28. The blast unit 57 includes a rotary fan 58, and is providedat a position overlapping with the liquid storage unit 50 when viewingfrom the horizontal direction.

In this embodiment, a pair of the blast units 57 are provided in thewidth direction X of the print sheet P so that air-outlet ports thereofoppose both ends of the print sheet P in the width direction X with theprotruding portion 29 (see FIG. 1) on the mounting surface 28 interposedtherebetween at a center. A configuration in which only one blast unit57 is provided and the air-outlet port thereof has a shape continuing inthe width direction X of the print sheet P is also applicable.

The liquid storage unit 50 includes ink cartridges 51, 52, 53, and 54,which correspond to liquid storage members configured to store aplurality of types (four colors in this case) of ink respectively, and aframe member 55 which allows the respective ink cartridges 51, 52, 53,and 54 to be mounted thereon. The ink cartridges 51, 52, 53, and 54 eachare formed into a substantially rectangular parallelepiped shape havinga longitudinal direction, and the frame member 55 has a box shape havingan opening on one surface thereof. The ink cartridges 51, 52, 53, and 54are configured to be mounted in the frame member 55 via the openingthereof in an insertable/withdrawable manner. The inserting/withdrawingdirection corresponds to the longitudinal direction of the inkcartridges.

In this embodiment, the inserting/withdrawing directions of the inkcartridges 51, 52, 53, and 54 are directions along the width directionX. Therefore, the printer unit 12 includes an aperture, which is notillustrated, which exposes the opening of the frame member 55 whenviewing from the width direction X, and a storage unit cover 56 (seeFIG. 1) which is capable of opening and closing the aperture. Forexample, a user of the recording apparatus 11 is allowed to expose theaperture, which is not illustrated, by opening the storage unit cover 56(see FIG. 1), and insert and withdraw the ink cartridges 51, 52, 53, and54 with respect to the frame member 55 via the exposed aperture alongthe width direction X.

In this embodiment, the short direction, the longitudinal direction, anda thickness direction of each of the ink cartridges 51, 52, 53, and 54are oriented in the vertical direction Z, the width direction X, and thehorizontal direction which extends along the discharging direction Y,respectively, in a state in which the ink cartridges 51, 52, 53, and 54are mounted in the frame member 55. The ink cartridges 51, 52, 53, and54 have the same length in the short direction (vertical direction Z)and are mounted in the frame member 55 in a line in the thicknessdirection.

The ink cartridge 54 out of the ink cartridges 51, 52, 53, and 54 is anink cartridge which stores ink having the highest injection frequencyfrom the recording unit 23 (for example, black) and is arranged at thefarthest position from the medium discharge port 26 on the opposite sideto the mounting base 27. The ink cartridge 54 is thicker than other inkcartridges 51, 52, and 53 and is capable of storing a larger amount ofliquid than the storage amounts of ink in other ink cartridges 51, 52,and 53.

As illustrated in FIG. 2, a rectangular plate-shaped channel formingmember 61 is arranged between the recording unit 23 and the mountingbase 27 in the printer unit. The channel forming member 61 and themounting base 27 form part of the third medium supply channel 33, whichcorresponds to a reversing route configured to reverse the print sheetP. In other words, a lower surface of the mounting base 27 and an uppersurface of the channel forming member 61 form the third medium supplychannel 33. The channel forming member 61 is inclined so as to beincreased in height as it proceeds to the discharging direction Y.

A communication route 62 diverged from an upstream end of the curvedchannel 34A of the medium discharge channel 34 and extending to themedium transport unit 15 is provided in the printer unit 12. Thecommunication route 62 is provided with a communication transport rollerpair 63 configured to transport the print sheet P in the communicationroute 62 toward the medium transport unit 15. A switching flap 64 isprovided at a diverging portion between the medium discharge channel 34and the communication route 62. The switching flap 64 is capable ofswitching the route of the print sheet P being transported in the mediumdischarge channel 34 either toward the curved channel 34A or toward thecommunication route 62.

The switching flap 64 is configured to be displaced between a positionfor introducing the print sheet P having been printed by the recordingunit 23 and being transported along the medium discharge channel 34toward the curved channel 34A (a position indicated by a solid line inFIG. 2) and a position for introducing the print sheet P toward thecommunication route 62 (a position indicated by a two-dot chain line inFIG. 2).

The recording apparatus 11 includes a control unit 65 configured tocontrol the entire recording apparatus 11 in an overall manner.

Next, a configuration of the medium transport unit 15 will be describedin detail.

As illustrated in FIG. 3, the medium transport unit 15 is provided witha main body case 70 having parallelepiped shape. An upstream route 71 isprovided on an upper portion of the main body case 70 so as to extendfrom the printer unit 12 side, which corresponds to the upstream side,toward the finisher 16, which corresponds to the downstream side. Theupstream route 71 is connected at an upstream end thereof to adownstream end of the communication route 62, and the print sheet Ptransported from the communication route 62 is transported therethrough.

A downstream end of the upstream route 71 is curved downward. A skiproute 72 is diverged from a beginning of the curve, which corresponds tothe midpoint of the upstream route 71 and extends toward the finisher16. A skip flap 73, which is an example of a skip switching unitconfigured to selectively switch the route so that the print sheet P inthe upstream route 71 is transported either toward the downstream end ofthe upstream route 71 or toward the skip route 72 is provided at thediverging point to the upstream route 71 and the skip route 72.

The skip flap 73 is configured to displace between a position forintroducing the print sheet P in the upstream route 71 toward thedownstream end of the upstream route 71 (a position indicated by a solidline in FIG. 3) and a position for introducing the print sheet P towardthe skip route 72 (a position indicated by a two-dot chain line in FIG.3). An upstream sensor 74 configured to detect an end of the print sheetP transported in the upstream route 71 is provided in the upstream route71 at a position immediately upstream side of the skip flap 73.

An upstream end of a first guide route 75, an upstream end of a secondguide route 76, and an upstream end of an intermediate route 77 areconnected to the downstream end of the upstream route 71. The firstguide route 75 is curved downward while extending from the downstreamend of the upstream route 71 toward the finisher 16.

The second guide route 76 is curved downward while extending toward theprinter unit 12 from the downstream end of the upstream route 71. Theintermediate route 77 extends straight downward from the downstream endof the upstream route 71, and is arranged between the first guide route75 and the second guide route 76.

A pair of guide flaps 78 as an example of a guide switch unit configuredto selectively switch the route so that the print sheet P transportedthrough the upstream route 71 is transported to one of the first guideroute 75, the second guide route 76, and the intermediate route 77 isprovided at the downstream end of the upstream route 71. The pair ofguide flaps 78 are configured to be displaced among a position forintroducing the print sheet P in the upstream route 71 to the firstguide route 75 (a position indicated by a solid line in FIG. 3), aposition for introducing the print sheet P to the second guide route 76(a position indicated by a two-dot chain line in FIG. 3), and a positionfor introducing the print sheet P to the intermediate route 77 (aposition indicated by a dot-and-dash line in FIG. 3).

An upstream end of a first switchback route 79 is connected to thedownstream end of the first guide route 75. Therefore, the first guideroute 75 is configured to introduce the print sheet P in the upstreamroute 71 to the first switchback route 79 arranged on the downstreamside of the upstream route 71. The first switchback route 79 extendsstraight downward from the downstream end of the first guide route 75.The first switchback route 79 is opened at a downstream end thereof, andis configured to be capable of receiving the print sheet P having amaximum printable (recordable) size for the recording unit 23 (see FIG.2).

An upstream end of a first discharge route 80 from which the print sheetP transported from the first guide route 75 to the first switchbackroute 79 is discharged is connected to the upstream end of the firstswitchback route 79, and the downstream end of the first discharge route80 is connected to the downstream end of the intermediate route 77 so asto join together. The first discharge route 80 has a semi-arc shapeprotruding toward the guide flaps 78, which correspond to the upperside, and has a length shorter than the first switchback route 79.

A first restriction flap 81 is provided at the downstream end of thefirst guide route 75. The first restriction flap 81 allows a movement ofthe print sheet P from the first guide route 75 to the first switchbackroute 79, but restricts the movement of the print sheet P from the firstswitchback route 79 to the first guide route 75. The first restrictionflap 81 is biased in the direction that closes the downstream end of thefirst guide route 75 constantly by a biasing force applied by a biasingmember, which is not illustrated.

When the print sheet P is transported from the first guide route 75 tothe first switchback route 79, the first restriction flap 81 isdisplaced in the direction that opens the downstream end of the firstguide route 75 against a biasing force applied by the biasing member,which is not illustrated, by a force that transports the print sheet P.When the print sheet P is transported from the first switchback route 79toward the first guide route 75, the print sheet P is introduced to thefirst discharge route 80 while being restricted to move toward the firstguide route 75 by the first restriction flap 81.

A first switchback roller pair 82 configured to be rotatable in bothforward and reverse directions is provided in the first switchback route79 at a position biased to the upstream end from a center portion.Therefore, the first switchback roller pair 82 is configured to becapable of transporting the print sheet P in the both forward andreverse directions. A first switchback sensor 83 is provided in thefirst switchback route 79 between the first switchback roller pair 82and the first restriction flap 81. The first switchback sensor 83 isconfigured to detect the end of the print sheet P being transported inthe first switchback route 79.

An upstream end of a second switchback route 85 is connected to thedownstream end of the second guide route 76. Therefore, the second guideroute 76 is configured to introduce the print sheet P in the upstreamroute 71 to the second switchback route 85 arranged on the downstreamside of the upstream route 71. The second switchback route 85 extendsstraight downward from the downstream end of the second guide route 76.The second switchback route 85 is opened at a downstream end thereof,and is configured to be capable of receiving the print sheet P havingthe maximum printable (recordable) size for the recording unit 23 (seeFIG. 2).

An upstream end of a second discharge route 86 from which the printsheet P transported from the second guide route 76 to the secondswitchback route 85 is discharged is connected to the upstream end of asecond switchback route 85, and the downstream end of the seconddischarge route 86 is connected to the downstream end of theintermediate route 77 so as to join together. The second discharge route86 has a semi-arc shape protruding toward the guide flaps 78, whichcorrespond to the upper side, and has a length shorter than the secondswitchback route 85. In this embodiment, the first switchback route 79and the second switchback route 85 have the same length and the firstdischarge route 80 and the second discharge route 86 have the samelength.

A second restriction flap 87 is provided at the downstream end of thesecond guide route 76. The second restriction flap 87 allows a movementof the print sheet P from the second switchback route 85 to the secondguide route 76, but restricts the movement of the print sheet P from thesecond switchback route 85 to the second guide route 76. The secondrestriction flap 87 is biased in the direction that closes thedownstream end of the second guide route 76 constantly by a biasingforce applied by a biasing member, which is not illustrated.

When the print sheet P is transported from the second guide route 76 tothe second switchback route 85, the second restriction flap 87 isdisplaced in the direction that opens the downstream end of the secondguide route 76 against a biasing force applied by the biasing member,which is not illustrated, by a force that transports the print sheet P.In contrast, when the print sheet P is transported from the secondswitchback route 85 toward the second guide route 76, the print sheet Pis introduced to the second discharge route 86 while being restricted tomove toward the second guide route 76 by the second restriction flap 87.

A second switchback roller pair 88 configured to be rotatable in bothforward and reverse directions is provided in the second switchbackroute 85 at a position biased to the upstream end from a center portion.Therefore, the second switchback roller pair 88 is configured to becapable of transporting the print sheet P in the both forward andreverse directions. A second switchback sensor 89 is provided in thesecond switchback route 85 between the second switchback roller pair 88and the second restriction flap 87. The second switchback sensor 89 isconfigured to detect the end of the print sheet P being transported inthe second switchback route 85.

The intermediate route 77, the first discharge route 80, and the seconddischarge route 86 are joined together at downstream ends thereof, andan upstream end of a downstream route 90 is connected to a junction Gthereof. Therefore, the intermediate route 77 connects the downstreamend of the upstream route 71 and the upstream end of the downstreamroute 90.

The downstream route 90 extends straight downward from the junction G soas to pass between the first switchback route 79 and the secondswitchback route 85, and then U-turns toward the finisher 16 so as to goaround the lower side of the downstream end of the first switchbackroute 79. Subsequently, the downstream route 90 extends straight upwardalong the finisher 16, joins together with the downstream end of theskip route 72, and is connected at a downstream end thereof to thefinisher 16.

As described above, the skip route 72 extending from the midpoint of theupstream route 71 curves gently upward as it proceeds to the downstreamend thereof and joins at the downstream end thereof with a downstreamend portion (midpoint) of the downstream route 90. Therefore, the skiproute 72 is capable of introducing the print sheet P in the upstreamroute 71 to the downstream route 90 without passing through theintermediate route 77, the first discharge route 80, and the seconddischarge route 86. A plurality of transport roller pairs 91 capable oftransporting the print sheet P are arranged in the upstream route 71,the skip route 72, and the downstream route 90 at proper intervals.

As illustrated in FIG. 2 and FIG. 3, the plurality of transport rollerpairs 91, the first switchback roller pair 82, the second switchbackroller pair 88, and the communication transport roller pair 63 areconfigured to be driven to rotate upon a transmission of a drive forcefrom a motor 92 arranged in the main body case 70 via an electricclutch, which is not illustrated. In addition, the skip flap 73, thepair of guide flaps 78, and the switching flap 64 are configured to bedisplaced upon a transmission of a drive force from the motor 92 via theelectric clutch, which is not illustrated.

The upstream sensor 74, the first switchback sensor 83, the secondswitchback sensor 89, the motor 92, and the above-described electricclutch (not illustrated) are electrically connected to the control unit65. The control unit 65 drives and controls the motor 92 and theabove-described electric clutch (not illustrated) on the basis ofsignals transmitted from the upstream sensor 74, the first switchbacksensor 83, and the second switchback sensor 89.

The postprocessing to be performed by the finisher 16 includes sorting,folding, stapling, punching, and aligning that aligns the ends of theprinted print sheets P sequentially transported from the mediumtransport unit 15. A finisher configured to perform at least one of theabove-described processes may also be provided.

An operation to be effected when reversing the print sheet P printed bythe recording unit 23 and transporting the same to the finisher 16 withthe medium transport unit 15 will be described below.

As illustrated in FIG. 2 and FIG. 3, the print sheet P printed by therecording unit 23 is transported toward downstream along the mediumdischarge channel 34 in a state in which the recording surface (printingsurface) faces upward. At this time, the switching flap 64 is displacedto a position for opening an upstream end side of the communicationroute 62, whereby the print sheet P in the medium discharge channel 34is introduced into the communication route 62 by the switching flap 64.

The print sheet P introduced to the communication route 62 istransported by the communication transport roller pair 63 to theupstream route 71 of the medium transport unit 15 along thecommunication route 62. In the description given below, P1 is a firstprint sheet out of the print sheets P to be sequentially transported tothe upstream route 71 and, in the same manner, P2 is a second printsheet, P3 is a third print sheet, and P4 is a fourth print sheet.

As illustrated in FIG. 3, when the skip flap 73 is displaced to aposition for closing the upstream end side of the skip route 72, thefirst print sheet P1 transported to the upstream route 71 is introducedto the downstream end of the upstream route 71 by the skip flap 73. Atthis time, since the pair of guide flaps 78 are displaced to positionsfor introducing the print sheet P1 in the upstream route 71 to the firstguide route 75, the print sheet P1 in the upstream route 71 passesthrough the first guide route 75 and is transported to the firstswitchback route 79 as illustrated in FIG. 4A.

Subsequently, when the print sheet P1 passes over the upstream route 71,the second print sheet P2 is transported to the upstream route 71, andthe pair of guide flaps 78 are displaced to positions for introducingthe print sheet P2 in the upstream route 71 to the second guide route76. Subsequently, as illustrated in FIG. 4B, the print sheet P1 istransported to the first switchback route 79 by the first switchbackroller pair 82 rotating forward, and when a trailing edge of the printsheet P1 in a direction of travel is detected by the first switchbacksensor 83, the first switchback roller pair 82 is rotated reversely. Atthis time, the print sheet P2 is transported from the upstream route 71to the second guide route 76.

Subsequently, as illustrated in FIG. 4C, when the print sheet P2 passesover the upstream route 71, the third print sheet P3 is transported tothe upstream route 71, and the pair of guide flaps 78 are displaced topositions for introducing the print sheet P3 in the upstream route 71 tothe first guide route 75. In contrast, when the first switchback rollerpair 82 are rotated reversely, the print sheet P1 in the firstswitchback route 79 passes through the first discharge route 80 and istransported to the downstream route 90. In this transport process, theprint sheet P1 is reversed. At this time, the print sheet P2 transportedto the second guide route 76 is transported to the second switchbackroute 85 by the second switchback roller pair 88 rotating forward.

Subsequently, as illustrated in FIG. 5A, the print sheet P2 istransported to the second switchback route 85 by the second switchbackroller pair 88 rotating forward, and when a trailing edge of the printsheet P2 in the direction of travel is detected by the second switchbacksensor 89, the second switchback roller pair 88 is rotated reversely. Atthis time, the print sheet P3 is transported from the upstream route 71to the first guide route 75, and the print sheet P1 is transporteddownstream side along the downstream route 90.

Subsequently, as illustrated in FIG. 5B, when the print sheet P3 passesover the upstream route 71, the fourth print sheet P4 is transported tothe upstream route 71, and the pair of guide flaps 78 are displaced topositions for introducing the print sheet P4 in the upstream route 71 tothe second guide route 76. In contrast, when the second switchbackroller pair 88 are rotated reversely, the print sheet P2 in the secondswitchback route 85 passes through the second discharge route 86 and istransported to the downstream route 90. In this transport process, theprint sheet P2 is reversed.

At this time, the print sheet P3 transported to the first guide route 75is transported to the first switchback route 79 by the first switchbackroller pair 82 rotating forward. Furthermore, at this time, the printsheet P1 is transported further downstream side along the downstreamroute 90.

In this manner, the print sheet P printed by the recording unit 23 isreversed by the medium transport unit 15 and is sequentially transportedto the finisher 16 in a state in which the recording surface facesdownward. Subsequently, the print sheets P are sorted, folded, stapled,punched or aligned by the finisher 16.

In the case where the print sheet P printed by the recording unit 23 isnot reversed by the medium transport unit 15, but is transported to thefinisher 16 as illustrated in FIG. 3, transport of the print sheet P isperformed in a state in which the pair of guide flaps 78 are displacedto positions for introducing the print sheet P in the upstream route 71to the intermediate route 77. In other words, the print sheet Ptransported to the upstream route 71 is transported to the finisher 16passing through the intermediate route 77 and the downstream route 90.In this configuration, even a printed print sheet P which does not haveto be reversed is transported along the intermediate route 77 and thedownstream route 90, so that a natural drying time for the paper P isensured.

In addition, in the case where the print sheet P printed by therecording unit 23 is rapidly transported to the finisher 16 by themedium transport unit 15 as illustrated in FIG. 3, transport of theprint sheet P is performed in a state in which the skip flap 73 isdisplaced to the position for opening the upstream end side of the skiproute 72. In other words, the print sheet P transported to the upstreamroute 71 is transported to the finisher 16 passing through the skiproute 72 and a downstream end portion (part) of the downstream route 90.In this case, since the skip route 72 simply curves gently upward towardthe downstream end thereof, this configuration is convenient for thecase where the medium can hardly be curved significantly such as a thickpaper.

According to the embodiment described in detail thus far, the followingadvantageous effects are achieved.

(1) In the medium transport unit 15, the downstream route 90 passesbetween the first switchback route 79 and the second switchback route85, and the upstream end thereof is connected to the junction G of thedownstream ends of the first discharge route 80 and the second dischargeroute 86. In addition, the length of the first discharge route 80 isshorter than the length of the first switchback route 79, and the lengthof the second discharge route 86 is shorter than the length of thesecond switchback route 85. Therefore, since the lengths of the firstdischarge route 80 and the second discharge route 86 may be reducedcompared with those in the related art, and hence the medium transportunit 15 can be reduced in size.

(2) The medium transport unit 15 includes the skip route 72 divergedfrom the midpoint of the upstream route 71, joined to the downstream endportion of the downstream route 90, and configured to introduce theprint sheet P in the upstream route 71 to the downstream end of thedownstream route 90, and the skip flap 73 configured to selectivelyswitch the route so that the print sheet P in the upstream route 71 istransported either toward the downstream end of the upstream route 71 ortoward the skip route 72.

Therefore, by switching the skip flap 73 toward the skip route 72 side,the print sheet P in the upstream route 71 can be transported rapidlythrough the skip route 72 to the downstream end portion of thedownstream route 90 without passing through the intermediate route 77,the first discharge route 80, and the second discharge route 86.

(3) The medium transport unit 15 is provided with the intermediate route77 configured to connect the downstream end of the upstream route 71 andthe upstream end of the downstream route 90, and the pair of guide flaps78 are configured to selectively switch the route so that the printsheet P transported through the upstream route 71 is transported to oneof the first guide route 75, the second guide route 76, and theintermediate route 77. Therefore, by switching the pair of guide flaps78 toward the intermediate route 77, the print sheet P in the upstreamroute 71 can be rapidly transported to the upstream end of thedownstream route 90 through the intermediate route 77 without passingthrough the first guide route 75 and the second guide route 76.

(4) In the medium transport unit 15, the length of the first guide route75 is shorter than the length of the first switchback route 79, and thelength of the second guide route 76 is shorter than the length of thesecond switchback route 85. Therefore, since the lengths of the firstguide route 75 and the second guide route 76 may be reduced comparedwith those in the related art, the medium transport unit 15 can bereduced in size.

(5) The recording apparatus 11 includes the recording unit 23 configuredto perform printing on the print sheet P, and the medium transport unit15, and the first switchback route 79 and the second switchback route 85are each configured to be capable of receiving the print sheet P havingthe maximum printable size for the recording unit 23. Therefore, theprint sheet P can be reliably received by the first switchback route 79and the second switchback route 85 as long as printing on the printsheet P by the recording unit 23 is possible.

(6) The recording unit 23 includes a line head capable of ejecting inkon the print sheet P transported at a high speed simultaneously over thesubstantially entire area in the width direction X at a lower portionthereof. Therefore, the high-speed printing is enabled. However, sincethe print sheet P absorbs ink over a wide surface area in a short time,the print sheet P tends to be curled in a wave shape in cross section.

If the print sheet P is curled, the print sheet P may jam in the courseof the transporting route or the postprocessing such as sorting andfolding may not be performed in the finisher 16. In this embodiment,with the provision of the medium transport unit 15, the printed printsheet P is dried while being transported in the transporting routeprovided in the medium transport unit 15, and curled shape of the printsheet P is disappeared and an original shape may be restored.

Modification

The above-described embodiment may be modified as follows.

As illustrated in FIG. 6, the medium transport unit 15 may be providedon an image reading apparatus 100 configured to read an image on theprint sheet P. In other words, the image reading apparatus 100 includesa scanner unit 101 configured to read the image on the print sheet P,the medium transport unit 15 arranged on the side portion of the scannerunit 101, and the finisher 16 arranged on the medium transport unit 15on a side portion provided on a side opposite to the scanner unit 101side. The scanner unit 101 includes a tray 102 on which print sheets Pare set, a transporting route 103 configured to transport the printsheets P set on the tray 102 to the upstream route 71 (see FIG. 3) ofthe medium transport unit 15, and a no-color transparent glass plate 104arranged at a midpoint of the transporting route 103 and forming a readsurface 104 a where an image on the print sheet P is read. A reader 105configured to read the image on the print sheet P passing over the readsurface 104 a through the glass plat 104 is arranged at a position rightunder the glass plate 104. The transporting route 103 includes a paperfeed roller 106 configured to feed the print sheet P set on the tray102, a paper feed roller pair 107 configured to feed the print sheet Pfed by the paper feed roller 106 onto the read surface 104 a, and apaper discharge roller pair 108 configured to discharge the print sheetP on the read surface 104 a to the medium transport unit 15. The firstswitchback route 79 and the second switchback route 85 of the mediumtransport unit 15 are opened at the downstream ends thereof so as to becapable of receiving the print sheet P having a maximum readable sizefor the reader 105. In this configuration, the print sheet P can bereliably received by the first switchback route 79 and the secondswitchback route 85 as long as the print sheet P can be read by thereader 105 is possible. In addition, the image reading apparatus 100configured as described above is convenient in the case of, for example,reading a plurality of the print sheets P (originals) which are stapled,and then stapling the print sheets P again. In other words, by removingthe staple once and setting the plurality of print sheets P on the tray102 of the image reading apparatus 100, the plurality of print sheets Pare sequentially transported to the finisher 16 by the medium transportunit 15 after the images on the plurality of print sheets P havesequentially been read by the reader 105, and then are stapled again.

-   -   In the medium transport unit 15, the intermediate route 77 may        be omitted.    -   In the medium transport unit 15, the skip route 72 may be        omitted.    -   In the medium transport unit 15, the length of the first        discharge route 80 may be longer than the length of the first        switchback route 79.    -   In the medium transport unit 15, the length of the second        discharge route 86 may be longer than the length of the second        switchback route 85.    -   In the medium transport unit 15, the length of the first guide        route 75 may be longer than the length of the first switchback        route 79.    -   In the medium transport unit 15, the length of the second guide        route 76 may be longer than the length of the second switchback        route 85.    -   In the medium transport unit 15, part of the print sheet P may        be protruded from opened downstream ends (lower ends) of the        first switchback route 79 and the second switchback route 85        when the print sheet P is received in the first switchback route        79 and the second switchback route 85.    -   In the medium transport unit 15, the length of the first        switchback route 79 and the second switchback route 85 may be        different from each other.    -   In the medium transport unit 15, the first discharge route 80        and the second discharge route 86 may be different lengths from        each other.    -   The first switchback route 79 and the second switchback route 85        each may be configured to include a space area. The first        switchback route 79 and the second switchback route 85        illustrated in FIG. 7A each include guide surfaces 110 a and 110        b facing each other on the upstream side of the first switchback        roller pair 82 and the second switchback roller pair 88 and have        no guide surface on the downstream side thereof but have a space        area. When the first switchback roller pair 82 and the second        switchback roller pair 88 pinch the print sheet P and rotate in        the forward direction or in the reverse direction, the print        sheet P is transported in a state in which the downstream side        of the print sheet P hangs therefrom. In this configuration, a        member having the guide surface is not required, and hence the        medium transport unit 15 may be reduced in size.    -   The first switchback route 79 and the second switchback route 85        each may be configured to include a curved route. The first        switchback route 79 and the second switchback route 85        illustrated in FIG. 7B each include guide surfaces 111 a and 111        b curved and facing each other on the downstream side of the        first switchback roller pair 82 and the second switchback roller        pair 88. When the first switchback roller pair 82 and the second        switchback roller pair 88 pinch the print sheet P and rotate in        the forward direction or in the reverse direction, the print        sheet P is transported in a state in which the downstream side        of the print sheet P is curved. In this configuration, the        length of the medium transport unit 15 in vertical direction of        the drawing may be reduced.    -   The first switchback route 79 and the second switchback route 85        may each have a roller at a downstream end thereof to cause the        downstream side of the print sheet to curve along an outer        peripheral surface of the roller. The first switchback route 79        and the second switchback route 85 in FIG. 7C include guide        surfaces 112 a and 112 b extending downward and facing each        other on the downstream side of the first switchback roller pair        82 and the second switchback roller pair 88, and each include a        roller 114 located at a position below the guide surface 112 b        and configured to be rotatable, and guide surface 113 connected        to the guide surface 112 a and curved along the outer peripheral        surface of the roller 114.

As illustrated in FIG. 7C, when the first switchback roller pair 82 andthe second switchback roller pair 88 each pinch the print sheet P androtate in a direction in which the print sheet P moves to the downstreamside, the print sheet P is transported with the downstream side thereofbeing wound around the outer peripheral surface of the roller 114. Whenthe first switchback roller pair 82 and the second switchback rollerpair 88 each rotate in a direction in which the print sheet P movestoward the upstream side, the print sheet P is transported with thedownstream side thereof being wound around the outer peripheral surfaceof the roller 114.

A configuration in which the roller 114 is rotated in conjunction withtiming of rotation of each of the first switchback roller pair 82 andthe second switchback roller pair 88 is also applicable. In thisconfiguration, the length of the medium transport unit 15 in a lateraldirection of the drawing may be reduced.

FIG. 8 is a view illustrating a structural frame format of a mediumtransport unit 15 a when viewing in the width direction X. The firstguide route 75 and the second guide route 76 illustrated in FIG. 3 arearranged so as to overlap entirely with the first discharge route 80 andthe second discharge route 86, respectively, in the vertical directionZ. However, a first guide route 121 and the second guide route 122 maybe arranged so as to partly overlap with a first discharge route 125 anda second discharge route 126, respectively, in the vertical direction Zas illustrated in FIG. 8.

An upstream route 120 is arranged from the printer unit 12 to the mediumtransport unit 15 a, and is arranged so as to be inclined downward as itproceeds to the downstream side in the transporting direction. Theupstream route 120 is diverged to the first guide route 121 and thesecond guide route 122 at a diverging point F1, which corresponds to adownstream end of the upstream route 120.

The first guide route 121 is diverged to a first switchback route 123and the first discharge route 125 at a diverging point F2, whichcorresponds to a downstream end of the first guide route 121. In thesame manner, the second guide route 122 is diverged to a secondswitchback route 124 and the second discharge route 126 at a divergingpoint F3, which corresponds to a downstream end of the second guideroute 122. The first discharge route 125 and the second discharge route126 join together on the downstream side thereof at a junction G1 andare connected to a downstream route 127.

The upstream route 120, the first guide route 121, the second guideroute 122, the first discharge route 125, the second discharge route126, and the downstream route 127 are each provided with a transportroller pair 130 configured to transport a print sheet to the downstreamside thereof. The first switchback route 123 and the second switchbackroute 124 are provided with switchback roller pairs 131 and 132configured to be capable of transporting the print sheet while switchingthe transporting direction to the downstream side or to the upstreamside, respectively.

A guide flap 150 that functions as a guide switch unit is provided atthe diverging point F1 so as to be pivotable as indicated by a solidline and a broken line to guide a print sheet (not illustrated)transported from the upstream side to the first guide route 121 or thesecond guide route 122.

A first restriction flap 151 and a second restriction flap 152 areprovided at the diverging points F2 and F3, respectively. The firstrestriction flap 151 and the second restriction flap 152 are biasedconstantly in directions that closes the downstream ends of the firstguide route 121 and the second guide route 122, respectively, by abiasing force applied by a biasing member, which is not illustrated.

When the print sheet is transported from the first guide route 121 tothe first switchback route 123, the first restriction flap 151 isdisplaced in a direction that opens the downstream end of the firstguide route 121 against a biasing force applied by the biasing member bya force that transports the print sheet. In contrast, when the printsheet is transported from the first switchback route 123 toward thefirst guide route 121, the print sheet is introduced into the firstdischarge route 125 while restricting the print sheet from moving to thefirst guide route 121 by the first restriction flap 151.

In the same manner, when the print sheet is transported from the secondguide route 122 to the second switchback route 124, the secondrestriction flap 152 is displaced in the direction that opens thedownstream end of the second guide route 122 against a biasing forceapplied by the biasing member by the force that transports the printsheet. In contrast, when the print sheet is transported from the secondswitchback route 124 toward the second guide route 122, the print sheetis introduced to the second discharge route 126 while restricting theprint sheet from moving to the second guide route 122 by the secondrestriction flap 152.

The first guide route 121 has a curved shape protruding upward. An upperportion of the second guide route 122 has a curved shape protrudingtoward the finisher 16, and a lower portion of the second guide route122 has a curved shape protruding toward the printer unit 12. In otherwords, the second guide route 122 is arranged so that the shape viewedfrom the width direction X is curved into an S shape.

The first guide route 121 is arranged so as to overlap partly with thefirst discharge route 125 in the vertical direction Z. In the samemanner, the second guide route 122 is arranged so as to overlap partlywith the second discharge route 126 in the vertical direction Z.

The diverging point F1 is located at a position biased to the printerunit 12 above the position of the junction G1.

The diverging point F2 is located at a position above the divergingpoint F3 on the finisher 16 side.

Therefore, as indicated by a dot-and-dash line J1 that connects thediverging point F1 and the junction G1 and a two-dot chain line J2 thatconnects the diverging point F2 and the diverging point F3, aconfiguration of a closed circular route formed by the first guide route121, the second guide route 122, the first discharge route 125, and thesecond discharge route 126 has an inclined shape in the verticaldirection Z as a whole.

The first switchback route 123 is formed on the downstream side of thediverging point F2, and includes guide surfaces 123 a and 123 b facingeach other and guide surfaces 123 c, 123 d, and 123 e formedcontinuously on the downstream side of the guide surface 123 a. Thesurface facing the guide surfaces 123 c, 123 d, and 123 e is notprovided, the guide surfaces 123 c and 123 d are opened on the printerunit 12 side, and the guide surface 123 e is opened on the upper side.The length of the first switchback route 123 is longer than the lengthsof the first guide route 121 and the first discharge route 125.

The print sheet is guided by the guide surfaces 123 a and 123 b facingeach other in the upper portion of the first switchback route 123, andis guided by the guide surfaces 123 c, 123 d, and 123 e having differentangle of inclination in the vertical direction Z in the lower portion ofthe first switchback route 123. Therefore, the print sheet transportedby the switchback roller pair 131 is bent as indicated by a broken line.

The second switchback route 124 is formed on the downstream side of thediverging point F3 and includes guide surfaces 124 a and 124 b facingeach other, and the print sheet transported by a switchback roller pair132 is guided thereby. The print sheet longer than the guide surfaces124 a and 124 b is bent as indicated by a broken line along an innerside surface 140 and an inner bottom surface 141 of a main body case 70a in a state of being pinched by the switchback roller pair 132.Therefore, when a long print sheet is transported by the switchbackroller pair 132, the inner side surface 140 and the inner bottom surface141 function as the guide surfaces in the second switchback route 124.

The downstream route 127 passes from the junction G1 between the firstswitchback route 123 and the second switchback route 124, and U-turnsupward so as to go around the lower side of the first switchback route123. The downstream route 127 extends straight upward along an innerside surface 142 of the main body case 70 a, protrudes toward theprinter unit 12 and curved, and then is arranged so as to be directedtoward the finisher 16.

The first switchback route 123, the second switchback route 124, and thedownstream route 127 include curved portions W1, W2, and W3 protrudingin the same direction (toward the finisher 16).

The printer unit 12, the finisher 16, and an enclosure (housing) of themedium transport units 15 and 15 a may be configured integrally or maybe configured to be separable.

With the configuration of the transporting route provided in the mediumtransport unit 15 a as described with reference to FIG. 8 thus far, thelength of the transporting route in the vertical direction Z and thetransporting direction are reduced to restrict an increase in size ofthe recording apparatus.

-   -   The medium may be only the print sheets P, but also cloth and        plastic films.    -   In the embodiment described above, the recording apparatus 11        may be a fluid ejecting apparatus configured to perform        recording by ejecting and discharging fluids other than ink        (including liquids, liquid-state materials formed by a liquid        with particles of a functional material dispersed or mixed        therein, flowing-state materials such as gel, and solids that        can be flowed and ejected as a fluid). For example, a        liquid-state material ejecting apparatus configured to perform        recording by ejecting a liquid-state material including        materials such as electrode materials or color materials (pixel        materials) used for manufacturing liquid-crystal displays, EL        (electro luminescence) displays, and surface-emitting displays        in a form of dispersion or dissolution. Also, a flowing-state        material ejecting apparatus configured to eject a flowing-state        material such as gel (for example, physical gel).

The invention may be applied to one of these fluid ejection apparatuses.The term “fluid” in the specification is an idea not including fluidscomposed only of gas, and the fluid includes, for example, liquids(including inorganic solvent, organic solvent, solution, liquid-stateresin, liquid-state metal (metallic melt) and the like), liquid-statematerials and flowing-state materials.

The entire disclosure of Japanese Patent Application No.: 2014-217046,filed Oct. 24, 2014 and 2015-065903, filed Mar. 27, 2015 are expresslyincorporated by reference herein.

What is claimed is:
 1. A medium transport unit comprising: an upstreamroute in which a medium is transported; a first switchback routearranged on a downstream side of the upstream route; a second switchbackroute arranged on the downstream side of the upstream route; a firstguide route configured to introduce the medium in the upstream route tothe first switchback route; a second guide route configured to introducethe medium in the upstream route to the second switchback route; a guideswitch unit configured to selectively switch the route so that themedium transported through the upstream route is transported to one ofthe first guide route and the second guide route; a first dischargeroute configured to discharge the medium from the first switchbackroute; a second discharge route configured to discharge the medium fromthe second switchback route; and a downstream route passing between thefirst switchback route and the second switchback route and having anupstream end connected to a junction of downstream ends of the firstdischarge route and the second discharge route.
 2. The medium transportunit according to claim 1, wherein at least one of a condition that alength of the first discharge route is shorter than a length of thefirst switchback route and a condition that a length of the seconddischarge route is shorter than the second switchback route issatisfied.
 3. The medium transport unit according to claim 2, wherein atleast one of a condition that a length of the first guide route isshorter than a length of the first switchback route and a condition thata length of the second guide route is shorter than the second switchbackroute is satisfied.
 4. The medium transport unit according to claim 1,further comprising: a skip route diverged from a midpoint of theupstream route and joining to a midpoint of the downstream route tointroduce the medium in the upstream route without passing through thefirst guide route and the second guide route; and a skip switching unitconfigured to selectively switch the route of the medium in the upstreamroute so as to be transported toward one of a downstream end of theupstream route and the skip route.
 5. The medium transport unitaccording to claim 1, further comprising: an intermediate routeconnecting downstream end of the upstream route and an upstream end ofthe downstream route, wherein the guide switch unit selectively switchesthe route so that the medium transported through the upstream route istransported to one of the first guide route, the second guide route, andthe intermediate route.
 6. A recording apparatus comprising: a recordingunit configured to perform recording on a medium; and a postprocessingunit configured to perform postprocessing on the medium on whichrecording is performed by the recording unit, wherein the recording unitand the postprocessing unit are coupled by the medium transport unitaccording to claim
 1. 7. The recording apparatus according to claim 6,wherein the first switchback route and the second switchback route areeach configured to be capable of receiving the medium having a maximumrecordable size for the recording unit.
 8. An image reading apparatuscomprising: a reader configured to read an image of a medium; and themedium transport unit according to claim 1, wherein the first switchbackroute and the second switchback route are each configured to be capableof receiving the medium having a maximum readable size for the reader.9. The recording apparatus according to claim 1, wherein when a mediumtransported ahead is discharged from the first switchback route to thefirst discharge route, a medium transported subsequently is transportedfrom the upstream route to the second guide route.